Shipping container with interlocking flaps



Patented Nov. 10, 1970 3,539,090

INVENTOR ROBERT Q BLASDELL BY 9016.. Ma Rue ATTORNEY United States Patent Robert O. Blasdell Birmingham, Michigan 790,377

Jan. 10, 1969 Nov. 10, 1970 The Mead Corporation Dayton, Ohio a corporation of Ohio [72] Inventor [21,] Appl. No. [22] Filed [45] Patented [73] Assignee [54] SHIPPING CONTAINER WITH INTERLOCKING FLAPS 5 Claims, 4 Drawing Figs,

[52] U.S. Cl 229/38, 229/39 [51] Int. Cl 865d 5/08 [50] Field ofSearch 229/38, 39, 37

[56] References Cited UNITED STATES PATENTS 2,666,567 1/1954 Farrell 229/39X 3,297,230 1/1967 Stegner 229/38 Primary Examiner-David M. Bockenek Attorney-John W. Donahue ABSTRACT: A shipping container which may be made on a printer-slotter and set up with the top flaps in a self closing interlocking arrangement. Flexure creases are provided in two opposed flaps for outwardly initiated closure.

SHIPPING CONTAINER WITH INTERLOCKING FLAPS BACKGROUND OF THE INVENTION playback senses setting that in I This invention relates to the field of shipping containers,

and more particularly to shipping containers having interlocking flaps for self locking closure.

Shipping containers are generally constructed from corrugated board, solid fibreboard, or other relatively stiff sheet material. The containers are usually closed with staples, glue, or other nonintegral fastening means, but frequently there may be employed any one of a variety of self locking closures. Typical of such closures are the structures disclosed in Acker US. Pat. No. 2,713,965, in Parker US. Pat. No. 3,101,882, and in Reeves US. Pat. No. 3,178,096.

While many efficient self locking closures are presently known, they are usually alike in that locking engagement is achieved by an inward pushing action. So far as is known the only exceptions are tab-type closures which generally cannot provide the load carrying capability of the interlocking flap configuration. It is apparent that inwardly pushed flap closures may function as automatic bottoms, but that they cannot be used for top closure of fully loaded containers. Furthermore, most prior art interlocking flaps as typified by Acker and Reeves require die cutting in order to achieve the necessary configuration. It is most desirable, especially for very large containers, to employ flaps which can be cut on a printerslotter; that is, flaps having perpendicularly disposed slots rather than angular cutouts.

SUMMARY OF THEINVENTION This invention provides a shipping container and blank therefor with four interlocking flaps which may be cut on a printer-slotter and which may be engaged without an inward pushing action. To this end the four interlocking flaps are each provided with a pair of inwardly extending slots. The slots in each flap mate with the slots in the adjacent flaps thereby enabling interlocking engagement. Closure is outwardly initiated and is facilitated by provision of laterally extending flexure creases in one pair of opposed flaps.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a blank for assembly of the preferred container.

FIG. 2 is a perspective view of the inventive container with the engagement flaps in the initial insertion position.

FIG. 3 is a perspective view showing the container of FIG. 2 in the fully closed condition.

FIG. 4 is a partial elevation view in section taken along lines 44 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred blank for the practice of this invention is as generally designated by the numeral 1 of FIG. I. It is divided by transverse score lines 23, 24, and and longitudinal score lines 26 and 27 into a pair of side panels 2, 2, a first end panel 3, a second end panel 4, side flaps 5, 5, and I4, 14, first end flaps 6 and 15, and second end flaps 7 and 16. Flaps 5, 5, 6, and 7 are provided for interlocking top closure while flaps I4, 14, 15, and 16 are provided for interlocking bottom closure. The top closure flaps are provided with first side slots 8, 8, second side slots 9, 9, first end slots l0, l0, and second end slots 11, 11; the functions of which may be observed in container 29 of FIGS. 2 and 3. As viewed in the blank, all slots are cut in the transverse direction. For closure initiation as shown in FIG. 2 there are provided first and second flexure creases 12 and 13 in first and second end flaps 6 and 7 respectively. Slots 17 through 20 and flexure creases 21 and 22 provide a similar function for the bottom closure.

It will be observed that the first side slots interlock with the first end slots and that the second side slots interlock with the second end slots. Furthermore, in order to achieve full interlocking closure it is necessary that a special relationship be establishedbetween the inset and the reach of mating slots. As designated by the letter I of FIG. 1, the inset of any slot is the displacement of the slot axis from the nearest transverse edge ofthe parent flaps. The reach of any slot as indicated by the letter R of FIG. I is the distance from the slot inner end to the depending fold line (hinge line) of the parent flap. The required relation for full interlocking closure is that the inset of each slot be at least as great as the reach of the mating slot, and vice versa. In addition, as shown in FIG. 2 the erected container must have first side slots 8, 8 aligned for reception of first end flap 6 and the second side slots 9, 9 aligned for reception of second end flap 7. Satisfaction of this latter requirement necessitates an equal inset for the first side slots 8, 8 and an equal inset for the second side slots 9, 9.

In order to initiate closure as shown in FIG. 2 it is necessary not only to provide flexure creases I2 and 13, but also to observe a certain limitation with respect to those creases. This limitation can best be understood by reference to FIG. 4 which illustrates several stages in the closure sequence. It can be seen that the shorter the inset l of slot 9 the greater must be the displacement of the flexure crease 13 from fold line 26. In the limit as l approaches zero, flexure crease 13 must approach the mid point of flap 7. In general, therefore, the limitation upon the flexure creases is that they be displaced from their flap fold lines a distance at least as great as half of the amount by which the length of the parent flap exceeds the inset distance of the corresponding side slots.

Once the outwardly initiated closure action has begun, the progressing closure causes a slight distortion FIG. the end flaps. As shown in FIG. 4 for the fully closed condition, end flap 7 is slightly distorted by entry into slot 9 and then reversely distorted by the upper surface of the contained product 28. The end flap outer edges remain undistorted. grip For convenience and symmetry it is desirable that all slots have the same inset and the same length. Doing this in accordance with the previously mentioned limitations and keeping the slots as short as possible automatically results in all slots having a reach exactly equal to the fixed inset distance. As a further result, the required displacement of flexure creases l2 and 13 becomes a distance at least half the length of the slots. In practice it is desirable to maintain the flexure creases near the flap fold lines so that the preferred displacement is exactly half the slot length. and

Iclaim:

1. In a blank for a shipping container comprising two side panels, first and second end panels joined along transverse fold lines to the two side panels, two side flaps joined to the two side panels along longitudinal fold lines at the tops thereof, a first end flap joined to the first end panel along a longitudinal fold line at the top thereof, and a second end flap joined to the second end panel along a longitudinal fold line at the top thereof; a crease and slot arrangement for self locking closure comprising: a first and a second side slot extending transversely inward from the margin of each side flap, a pair of first end slots extending transversely inward from the margin of the first end flap, a pair of second end slots extending transversely inward from the margin of the second end panel, and longitudinal first and second flexure creases extending across the widths of the first and second end flaps respectively; the first side slots being inset an equal distance from their respective side flap edges, the second side slots being inset an equal distance from their respective side flap edges, each first end slot having a reach of extent up to the inset distance of the first side slots and an inset distance at least as great as the reach of the corresponding first side slot, the second end slots and second side slots being related in like manner as the first end slots and first side slots, the first flexure crease being displaced from the first end flap fold line a distance at least as great as half the amount by which the length of the first end flap exceeds the inset distance of the first side slots, and the second flexure crease being displaced from the second end flap fold line a distance at least as great as half the amount by which the length of the second end flap exceeds the inset distance of the second side slots.

2. The crease and slot FlG. of claim 1, all slots having an equal inset distance and a reach equal to the inset.

3. In a shipping container blank having side flaps and end flaps of equal length and an arrangement of creases and equal length slots according to claim 2, the improvement wherein both flexure creases are displaced from their respective flap fold lines a distance equal to half the slot length.

4. In a shipping container comprising two opposed side panels, a first end panel joined to the two side panels at one end thereof, a second end panel joined to the two side panels at the other end thereof, two side flaps each foldably joined to one side panel at the top thereof, a first end flap foldably joined to first end panel at the top thereof, and a second end flap foldably joined to the second end panel at the top thereof; a crease and slot arrangement for self locking closure comprising: two first side slots extending from the margins of the two side flaps, said first side slots being parallel to the first end panel and inset an equal distance therefrom; two second side slots extending from the margins of the two side flaps, said second side slots being parallel to the second end panel and inset an equal distance therefrom; a pair of first end slots extending from the margin of the first end flap in a direction parallel to the side panels and in interlocking engagement with the first side slots; a pair of second end slots extending from the margin of the second end flap in a direction parallel to the side panels and in interlocking engagement with the second UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,539,090

Dated November 10, 1970 Robert 0. Blasdell It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

At line 4, "flaps" should read of delete "and".

-- arrangement column delete Attest:

Edward M. Fletcher 3 Febuary 23, 1971 WILLIAM E- SGHUYIER, m-

G-omissioner of Patents 

